1. Field of the Invention
The present invention relates to disk drives and more particularly to a technique for minimizing adjacent track data loss from a shock event during a write operation in a disk drive.
2. Description of the Prior Art
In order to remain competitive, disk drive manufacturers must continually provide increased storage capacity in a host system which stores data on the disk drive while rigidly controlling disk drive manufacturing cost. Host systems conventionally access disk drives via an operating system which views and fills the disk drive as a sequentially ordered string of logical blocks, each identified by a logical block address. Disk drives map the logical block addresses to sectors located on concentric tracks of one or more disks in the disk drive. Because host systems tend to perform a large number of accesses in sequential logical block order, disk drives conventionally map sequential logical block addresses to sequential tracks.
One key to increased storage capacity is increasing track density, often expressed as tracks per inch or TPI. Market demand for increased storage capacity has pushed disk drive designers to increase the TPI of disk drives, thereby increasing the likelihood that a shock event during a write operation may cause the read/write head to wander toward an adjacent track and write over data stored on the adjacent track.
Accordingly, there exists a need for a method that enables a disk drive to minimize adjacent track data loss resulting from a shock event during a write operation without unnecessarily increasing the disk drive""s manufacturing cost.
The present invention may be embodied in a method for minimizing adjacent track data loss due to a shock event occurring during a write operation in a disk drive. The method includes providing a plurality of adjacent concentric data tracks, for storage of user data, that are spaced-apart by an inter-track distance. The plurality of data tracks is allocated into a first set and a second set such that the tracks of the first and second sets are interleaved physically with one another. A first series of logical block addresses are assigned to the first set of data tracks such that the first series of logical block addresses are consecutively numbered between successive ones of the first set of data tracks. A second series of logical block addresses, which consecutively follow the first series of logical block addresses, are assigned to the second set of data tracks such that the second series of logical block addresses are consecutively numbered between successive ones of the second set of data tracks. Because a host system stores data on a disk drive in a consecutive logical block sequence, the foregoing assignment of logical block addresses to the first and second sets of data tracks results in the disk drive postponing writing to the second set of data tracks, thereby reducing data loss due to a shock event causing adjacent track encroachment occurring prior to writing to the second set of data tracks.
Further, each data track of the first set may be separated from another data track of the first set by one data track of the second set. Also, the disk drive may postpone writing to the second set of data tracks by first writing user data to the data tracks of the first set until substantially all of the data tracks of the first set have been written with user data.
Additionally, the step of assigning a first series of logical block addresses may include assigning the logical block addresses starting from an inner-most data track of the first set to an outer-most data track of the first set and the step of assigning a second series of logical block addresses comprises assigning the logical block addresses from an outer-most data track of the second set to an inner-most data track of the second set. Alternatively, the first series of logical block addresses may be assigned starting from an outer-most data track of the first set to an inner-most data track of the first set and the second series of logical block addresses may be assigned from an inner-most data track of the second set to an outer-most data track of the second set.
Another embodiment of the invention may reside in a method of minimizing adjacent track data loss from shock events occurring during host write operations. The method may include providing a plurality of adjacent concentric cylinders that are spaced-apart by a distance and that each includes at least one data track designated for storage of user data. The plurality of cylinders may be allocated into a first set and a second set such that the cylinders of the first and second sets are interleaved physically with one another. A first series of consecutively numbered logical block addresses may be assigned to the first set of cylinders such that the first series of logical block addresses are associated with data tracks of the first set of cylinders. A second series of consecutively numbered logical block addresses, which consecutively follow the first series of logical block addresses, may be assigned to the second set of cylinders such that the second series of logical block addresses are associated with data tracks of the second set of cylinders. A host system generally initially writes data associated with the first series of logical block addresses and postpones writing data associated with the second series of logical block addresses, until data has been written which is associated with substantially all of the first series of logical block addresses. Thus, the logical block address allocation to the first and second sets of cylinders results in minimizing loss of user data due to shock events causing adjacent track encroachment during host write operations occurring prior to writing user data to the data tracks of the second set of cylinders.